1. Field of the Invention
This invention relates, in general, to a method and apparatus for treating threads and, in particular, to a new and useful method and device for crimping and subsequently cooling synthetic threads, particularly filament and foil threads.
2. Description of the Prior Art
A large number of devices and methods are already employed for crimping filament and foil threads. Garments are still crimped today, but almost exclusively according to the false wire method. In medium and coarse yarns destined for garments, the speed that can be achieved with the false wire method including the friction method are relatively low. For these and similar reasons, it has been tried to find a method which permits higher speeds, but also operates at an output sufficient for garments with a finer curved, more uniform and more stable crimp.
Methods are also known where the capillary threads are composed of two or more differently-shrinking components or which are cooled unidirectionally and crimped in a subsequent heat treatment by different shrinkage. These yarns have the disadvantage that the crimping stability is relatively low so that the risk of high crimping losses during the hard winding or during the further processing is very great. A crimping stability which is too low involves the risk of streakiness and curliness in a multifilar processing due to the varying crimping losses. Furthermore, these yarns have the disadvantage that the deformation of the capillary threads is not intensive so that the materials produced therefrom have a soapier feel than materials produced from false wire yarns.
Methods are also known where the threads are crimped in a compression chamber by a nozzle which acts to throw the thread against a baffle surface, by embossing rolls or by meshing gear wheels. The crimped yarns obtained with these methods do not melt which is a requirement for yarns used in the garment industry in most cases. This is due to substantially the fact that the crimping is too coarse and not uniform and not stable enough. In addition, the feel of the materials made therefrom is also too soapy, compared to the material made of false wire yarns.
For the production of carpet yarns on an individual scale, the following methods are used:
the compression chamber method, PA1 the gear wheel method, PA1 the air impact method, and PA1 the nozzle blowing method. PA1 a. intensive and finely curved deformation of the capillary threads; PA1 b. uniform heating of the capillary threads up to the center of the cross-section at the time of deformation; PA1 c. long and uniform maintenance of the intensive deformation in order to insure the necessary structural changes in the interior of the thread and PA1 d. uniform maintenance of the intensive deformation until the thread is cooled down to a temperature close to the freezing temperature. PA1 a. heating the texturizing thread in known manner up to the center of the cross section, for example, by means of heated rollers; PA1 b. preliminary crimping of the threads, for example, by starting the shrinking in differently shrinking threads (bicomponent threads), throwing against a baffle surface, embossing by means of finely-grooved embossing rollers, deformation between the tooth edges of gear wheels or in air or steam nozzles; PA1 c. production of a wadding from the precrimped threads; PA1 d. great compression of the wadding by reducing its volume; PA1 e. heat treatment of the highly compressed wadding by transporting the wadding through a heating zone and thereafter a cooling zone, and finally PA1 f. if necessary, reducing the crimping by a following heating zone in order to obtain a yarn of reduced stretchability, but high elasticity, that is, of great crimping stability.
For extremely high speeds, the yarns must be wound very hard. Otherwise, the bobbins will break out when the centrifugal force acting on them diminishes. In this case, a crimping loss during the winding caused by a too low crimping stability is unavoidable. The yarns thus no longer meet the quality requirements.